Rare metals such as rare non-ferrous metals, have been widely used in constructional materials, electronic material/magnetic materials, functional materials, etc. A value of the rare metal has become a point of focus, along with miniaturization and high performance, of recent electronic components. Countries producing the rare metals are concentrated, and it is therefore desirable to provide effective recycling of the rare metals, especially in resource-limited countries.
In these situations, a ceramic base material, such as used in a muffler of an automobile, a thermal power plant, a garbage incineration plant, etc., contains waste catalyst including rare metals such as palladium (Pd), platinum (Pt) and rhodium (Rh). A method for recovering rare metals from the waste catalyst with a high accuracy is a part of a conventional high temperature refining process. However, an effective method for recovering rare metals by a low temperature refining process has not as yet been established.
In a conventional rare metal recovery method, a waste fluorescent material containing rare metal components is first subject to a low degree mechanochemical treatment to elute components of yttrium (Y) and europium (Eu) in a weak acid, and subsequently subject to a high degree mechanochemical treatment to elute components of lanthanum (La), cerium (Ce) and terbium (Tb) in a weak acid to selectively separate the rare metal components (see Japanese Patent Provisional Publication No. 2000-192167).